Amplitude of a block oscillating on a spring

[drunknfox]

Homework Statement

a .25kg block oscillates on the end of a spring with a spring constant of 200N/m. If the oscillation is started by elongating spring to 0.15m and giving the block a speed of 3.0m/s. The amplitude is?

Homework Equations

omega= sqrt(k/m), Vm = (omega)Xm

The Attempt at a Solution

omega= sqrt (200/.25) = 28.28 (3m/s) = 28.28Xm (3/28.28) = .106

The correct answer is .18m..what am i missing?

 

[ehild]

The spring is stretched by 0.15 m and the block has 3 m/s speed at the same time. 0.15 is not the maximum displacement and 3 m/s is not the maximum speed. Calculate the energy, and get the maximum speed from it.

ehild